bug: password not found in secret manager

Hi Bux,

I would like `trsync_manager` to retrieve the Tracim instance password has described in the README:

> trsync_manager will try to get passwords from system secret manager with key `trsync::` and current logged user as user.

- In ~/.trsync.conf, I have a Tracim instance called `algoo`
- In Seahorse (Gnome's secret manager), I have created a password with description `trsync::algoo`
- But when I run `trsync_manager` it says:

```
ERROR trsync_core::config] Unable to read password from config for instance 'algoo.tracim.fr' and user 'yvan', this instance will be ignored : 'No matching entry found in secure storage'
```

Do you have a idea about what I am doing wrong?

Thanks,
Yvan